This invention relates to a fuel increasing system for an engine and more particularly an improved arrangement for providing supplemental fuel to an engine for certain running conditions.
It is well known to provide a charge forming system for an internal combustion engine that supplies a fuel/air charge to the engine for its running. However, internal combustion engines are called upon to run over a wide variety of load and speed ranges. If the charge forming system is designed so as to provide the appropriate fuel/air ratio under all of these conditions it can become quite complicated.
It has, therefore, been proposed to provide a fuel supply system for an internal combustion engine that employs a main charge former that supplies fuel and air to the engine for its normal running conditions. However, there is provided a fuel increasing or supplemental fuel system for the engine so as to provide additional fuel under certain running conditions such as starting, cold warm up or acceleration. A wide variety of supplemental fuel supply systems have been proposed.
It has been found that the supplemental fuel supply system for an engine can be most effective if the fuel is supplied to the engine under the pressure of a separate fuel pump. By employing separate fuel pumps, it is not necessary to rely on the suction of the engine induction system to insure that the appropriate amount of supplemental fuel can be delivered. However, when an additional fuel pump is provided, the system can become quite complicated and, in some instances, it may be difficult to meet the desired ends.
For example, one application in which a supplemental fuel supply system is employed is in conjunction with an outboard motor. It is well known, however, that outboard motors frequently employ remotely positioned fuel tanks. If the supplemental system incorporates a supplemental fuel pump that draws separate fuel from the remotely positioned tank, the conduitry and connectors for connecting the remote system to the powerhead of the outboard motor can become quite complicated. In addition, it is the normal practice when supplemental fuel pumps are employed to incorporate a pressure regulator that regulates the pressure by returning excess fuel to the fuel system. If the excess fuel must be returned to a remotely positioned tank, the system obviously becomes more complicated.
Although alternative systems have been proposed wherein the supplemental fuel pump draws fuel from a conduit somewhere in proximity to the engine, for example from the fuel filter or some other place in the conduit upstream of the charge formers, then the pressure variations caused by the main fuel pump and the supply of two different fuel lines from a common source can give rise to variations in fuel supply by both the main and the supplemental system. Also, if the pressure is regulated by return of the excess pressure back into the line upstream of the charge former, for example in the fuel filter, air bubbles may be generated in the fuel return line which can be ingested into the fuel supply system of either the main or the auxiliary systems giving rise to additional problems.
It is, therefore, a principal object of this invention to provide an improved and simplified supplemental fuel system for an internal combustion engine.
It is a further object of this invention to provide an improved, simplified supplemental fuel system that will not require excess conduitry nor will it have the disadvantages aforenoted.
It is a further object of this invention to provide an improved, simplified supplemental fuel system for an outboard motor.
It is a further object of this invention to provide a supplemental fuel system embodying a pump and pressure regulator that can be mounted easily on a single component of the engine and thus permit easy applicability to outboard motors.